Prince Harry and Meghan Markle currently reside in a cottage on the Kensington Palace grounds. After the announcement the couple are expecting their first child, it was speculated they would move into an apartment in the main palace following their tour of the Pacific, which finishes on Wednesday.

"[The] William and Harry double-act has naturally been supplanted by the two couples and their families," The Times’ source continues.

Both brothers have active roles within the Royal Family. However, when Prince William becomes the Prince of Wales following father Prince Charles' inevitable ascent to the throne, he will take on a lot of extra responsibility, including the role of 'Duchy of Cornwall'.

Royal correspondent Robert Jobson has predicted the Queen will stand aside to allow Prince Charles to become King in three years.

"I understand the Queen has given the matter considerable thought and believes that, if she is still alive at 95, she will seriously consider passing the reins to Charles," Jobson has previously said.

The Duke and Duchess of Sussex are expecting their first child in April, 2019. (Getty )

The Duke and Duchess of Sussex will have less expectations placed on them, but are expected to continue to forge their own paths, which have so far included mental health, disability, veterans and youth.

Another source tells The Times Prince William and Prince Harry's wish to operate independently of each other.

"They have become different people with different outlooks on life. Splitting the household is the obvious thing to do,” they explain.